1. Field
The present disclosure relates to a battery state control circuit including multiple rechargeable batteries, a battery state control device, and a battery pack.
2. Description of the Related Art
Conventionally, a battery pack in which multiple secondary batteries (cells) are connected in series is known, and the battery pack includes an electric circuit adapted to adjust battery voltages of the secondary batteries to ensure a uniform battery voltage for the secondary batteries.
In the battery pack according to the related art, the voltages of the secondary batteries are equalized by the electric circuit so as to ensure a uniform battery voltage, which can prevent characteristic differences between the secondary batteries due to manufacturing variations of the secondary batteries and due to cycle degradation or individual changes over time.
For example, JP 2011-182484-A discloses a secondary battery protection circuit including multiple switches connected in parallel to a plurality of secondary batteries, respectively. When the secondary batteries are being charged, the secondary battery protection circuit supplies energy to a secondary battery whose battery voltage is lower a predetermined return voltage.
In another example of JP 2011-083182-A, in a battery circuit including a switch connected to multiple secondary battery cells, electrical energy is transferred from at least one of the battery cells having a higher battery voltage to another of the battery cells having a lower battery voltage.
However, equalizing the battery voltages of the secondary batteries in accordance with the situation is not taken into account in the battery pack according to the above-described related art cases.